1. Field of the Invention
The present invention relates to a laser marking method for irradiating a laser beam onto a photosensitive material, i.e., a photographic photosensitive material such as an X-ray film or a thermally-developed photosensitive material, to form thereon a marking pattern, such as characters and symbols.
The present invention also relates to a photosensitive material having a marking pattern formed thereon and to a laser marking method for irradiating a laser beam from a laser onto an emulsion layer of a photosensitive material, in which an emulsion layer is formed on a surface of a base layer, to form thereon dot patterns in which the emulsion layer is thermally melted and deformed, whereby a marking pattern including visible characters or symbols is formed by a combination of the dot patterns.
The present invention also relates to a laser marking method that enables a one-dimensional barcode to be formed as a marking pattern.
The present invention also relates to a laser marking method for forming a marking pattern on a one-sided type photosensitive film, in which a surface layer including an emulsion layer is formed on one side of a support, such as PET, and an undersurface layer is formed on the other side.
Moreover, the present invention relates to a photosensitive material processing method for processing a photosensitive material from a roll into sheets of a predetermined size, and to a processed photosensitive material.
2. Description of the Related Art
As technology for marking characters and symbols onto a surface of a material using laser light, there is, for example, the technology disclosed in Japanese Patent Application Laid-Open Publication (JP-A) No. 10-305377. Also, in Japanese Patent No. 3191201 (referred to below as “prior art”), marking technology has been proposed in which a laser beam is irradiated onto a photosensitive material such as an X-ray film, dots are formed by causing fogging and deformation in a surface of the photosensitive material, and characters and symbols are formed by the dot arrangement.
In this prior art, the laser irradiation time (pulse width) per dot is set to at least 30 μsec or more in order to cause deformation or thermal fogging in order to raise visibility.
However, in relation to dot plotting, there exist no guidelines for dot forms and processing methods in order to obtain marking (characters or symbols) with good visibility. With respect to laser beam irradiation conditions, it has been necessary to experimentally determine irradiation target materials, laser types, and oscillation wavelengths as parameters.
There are also variations in the results of these experiments depending on the person judging visibility, management of conditions of laser irradiation devices cannot be done quantitatively (numerically), and it has been difficult to conduct stable marking.
In the case of an X-ray film, the original quality of the X-ray film is sometimes compromised by laser irradiation, in that the emulsion layer that has been scattered on the surrounding area by laser irradiation adheres to the film surface, the film is burned by the laser being irradiated again onto the portions to which the emulsion layer adheres, thermal fogging and light fogging are generated, and an image is formed while adhering to the emulsion layer surface, whereby those portions are whitely omitted (so-called white spots).
In order to eliminate these problems, it is best to conduct irradiation so that the emulsion layer does not scatter. However, even when scattering cannot be seen immediately after marking by laser irradiation, sometimes emulsion layer portions are separated in subsequent steps such as development. This is a phenomenon that can occur in a state in which a space has been generated between the emulsion layer and the base layer. Such separation exerts an enormous influence on visibility and leads to differences in evaluation, in which the film is deemed to be improper in an evaluation of visibility by a user, regardless of whether the film was deemed to be proper in an evaluation of visibility at the manufacturing stage.
Also, when characters and symbols are marked on a photosensitive material such as an X-ray film, a spot laser beam is irradiated onto the emulsion layer of the photosensitive material. Thus, minute air bubbles are generated in a process in which gelatin included in the emulsion layer and the like is melted by energy of the laser beam, whereby convex portions are formed. These convex portions become dots that are visible due to reflection of light being varied by numerous boundary films between the air bubbles, and characters and symbols are formed as a marking pattern by the arrangement of these dots.
In a photosensitive material such as X-ray film, sometimes the emulsion layer melted by the laser beam scatters on the area surrounding the irradiation position of the laser beam. When the scattered emulsion layer adheres to the surface of the photosensitive material, sometimes so-called white spots are generated when an image is formed at the portion to which the scattered emulsion layer adheres.
Also, when the laser beam is continuously irradiated, sometimes the scattered emulsion layer is burned by the laser beam and generates fogging. Such fogging lowers the product quality of the photosensitive material.
Moreover, in an X-ray film in which a PET support is used as a base layer and an emulsion layer is formed on the base layer, sometimes it becomes easy for the emulsion layer to separate from the base layer when the laser beam is irradiated and dots are formed. When it becomes easy for the emulsion layer to separate from the base layer, although visibility of the dots becomes high immediately after the dots have been formed, the emulsion layer separates and drops away from the base layer and visibility becomes extremely low when the film is developed. That is, when it becomes easy for the emulsion layer to separate from the base layer due to irradiation of the laser beam, sometimes the visibility of the characters and symbols formed on the X-ray film varies prior to and after development.
Although the aforementioned prior art proposes to secure visibility by limiting the irradiation conditions of the laser beam per dot, it offers no proposals for preventing troubles in quality resulting from irradiating the laser beam onto the photosensitive material and preventing variations in visibility prior to and after development.
Also, in the prior art, a laser beam oscillated at a low output is used in order to impart to the photosensitive material energy for forming proper dots. However, when a low-output laser is used, it takes time to impart the energy necessary to form the dots. That is, sometimes it becomes necessary to irradiate the laser beam for a long time, and when the laser beam is irradiated for a long time, sometimes heat is transmitted to the interior of the photosensitive material and causes the emulsion layer to separate from the base layer. Thus, sometimes variations in the visibility of the characters and symbols prior to and after development are caused.
When highly visible dots are formed on the X-ray film, it is necessary for the diameter of the dots to be of a predetermined value or higher. Thus, the prior art proposes forming highly visible dots by appropriately controlling the irradiation time of the laser beam. Also, setting the intervals between the dots to be within a predetermined range, it is possible to raise the visibility of the characters and symbols formed by the dot arrangement.
When the laser beam is irradiated onto the X-ray film and dots are formed, sometimes a space is generated between the base layer and the emulsion layer. Although this space improves the visibility of the dots immediately after the dots (marking pattern) have been formed on the X-ray film, the emulsion layer above the space separates from the base layer and the visibility of the dots is lowered. That is, the space generated between the base layer and the emulsion layer lowers the visibility of the dots at the stage when the film is used by a user.
Thus, when a laser beam is irradiated onto a photosensitive material such as an X-ray film and a marking pattern is formed, dot forms in which there are no variations in visibility between the stage when the dots are formed and from subsequent processing steps on are preferable.
Configurations in which various information is imparted by a marking pattern formed on a photosensitive material such as an X-ray film by a dot arrangement have been variously proposed.
An example of a symbol representing various information in place of characters and symbols is the barcode. So-called one-dimensional barcodes, which represent characters and symbols by a combination of lines of varying thickness and spaces, are common. By using this barcode, a large amount of information can be recorded in a limited space. Moreover, by automatically reading this information using a barcode reader in processing steps of the X-ray film, appropriate processing of the X-ray film based on the information recorded as a marking pattern becomes possible.
When a barcode is recorded on a photosensitive material such as an X-ray film using a spot laser beam emitted from a marking head, it is necessary to stop the conveyance of the X-ray film or to move the marking head to match the conveyance speed of the X-ray film.
That is, when a bar (line), and not dots, is formed on the X-ray film using a spot laser beam, it is necessary to irradiate the laser beam in a state in which the X-ray film has been relatively stopped with respect to the marking head.
However, when a barcode is recorded as the marking pattern at predetermined intervals on a rolled X-ray film, problems arise in that the time necessary to record the marking pattern becomes long when the conveyance of the X-ray film is stopped, processing time of the photosensitive material such as the X-ray film becomes long, and processing efficiency drops.
Also, when characters and symbols are marked on a photosensitive material such as an X-ray film, a spot laser beam is irradiated onto the side of the photosensitive material disposed with the emulsion layer. In this instance, it is possible to form highly visible dots by properly controlling the irradiation time of the laser beam.
When a laser beam is irradiated onto a photosensitive material and marking is conducted, sometimes dust generated at the time of processing and emulsion layer separated by irradiating the laser beam onto the photosensitive material adheres to the surface of the photosensitive material. When the laser beam is irradiated onto the photosensitive material in a state in which dust and separated emulsion layer (emulsion waste) adhere to the surface of the photosensitive material, the dust and the emulsion layer are burned by the energy of the laser beam and cause fogging in the photosensitive material. Also, when an image is exposed on the photosensitive material in a state in which the emulsion layer and the like adhere to the photosensitive material, so-called white spots are generated when the photosensitive material is developed.
However, it is necessary to conduct marking in an environment in which a high degree of cleanliness is maintained in order to prevent dust in the air from adhering to the surface of the photosensitive material at the time of marking, and this is extremely difficult in terms of cost and the environment in which the device is disposed.
Also, in the field of medicine, reducing the amount of processing fluid waste are desired from the standpoints of environmental safety and space efficiency. Thus, light photosensitive thermally-developed photosensitive materials for medical diagnoses and photographic technology in which a clear black color image having high resolution and sharpness can be formed by efficiently exposing the photosensitive material using a laser image setter or a laser imager have been proposed, and thermal-development systems that are simple and do not harm the environment have attracted attention.
Such light photosensitive thermally-developed photosensitive materials are photosensitive films in which layer that includes a photosensitive silver halide, a non-photosensitive organic silver salt, a thermal developing agent, and a binder is formed as a so-called emulsion layer on one side of a PET support, and have the property that the side disposed with the emulsion layer is easily damaged.
Thus, when laser processing is conducted and dust generated at the time of the laser processing and emulsion waste adheres to light photosensitive thermally-developed materials, there are problems in that, not only is fogging easily generated, but the surface is easily damaged by the dust and the emulsion waste.
With respect to sheets of photosensitive material such as an X-ray film, the photosensitive material is formed into sheets of a size that becomes a final mode by slitting and cutting a roll in which a wide and long photosensitive material is wound in a roll. Numerous sheets of the photosensitive material that has been processed into the sheets, which is the final mode, are stacked and packaged by a packaging material or accommodated in a magazine and packaged.
As a method of identifying sheets of the image recording material such as photosensitive material, proposals for adding identification information to each package unit have been made, such as affixing labels on which identification information is recorded to the packages in which the image recording material is packaged or to the magazine, or recording identification information on the image recording material of the bottommost layer among the stacked image recording material. Thus, it becomes easy to identify (specify) the image recording material in a single package unit and to grasp various information, and by automatic reading of the identification information, it becomes possible to clearly verify whether or not the image recording material is suited for the purpose of its use when the image recording material is to be used.
However, in these proposals, the labor for affixing the labels on which the identification information is recorded to the packaging material or to the magazine relies upon manual labor. Thus, there is the potential for a laborer to forget to affix the labels or erroneously affix the labels. When a laborer forgets to affix the labels or erroneously affixes the labels, it becomes impossible to judge whether or not the image recording material is of a type suited for the purpose of its use. Particularly when the identification information is automatically read and a laborer has forgotten to affix the labels or erroneously affixed the labels, sometimes the image recording material in a package unit is wasted. That is, when trouble arises with the image recording material, it becomes difficult to specify the image recording material, and it also becomes impossible to investigate the cause of the trouble without being able to trace the processing history.
Also, when identification information is burned in advance on the bottommost layer of the stacked image recording material, it is necessary to leave the image recording material on which the identification information is recorded until the very last. Because the identification information is not recorded on the other image recording material, identification becomes difficult when the image recording material on which the identification information is not recorded is removed from the package unit.